Troubleshooting Part by Part

Hello, I'm knee deep in troubleshooting my sons laptop repair. I used to be a fix it man for our local community college, not specifically computer repair, but from time to time it was part of the job and its been a while but I figured I would take a crack at it.

He says he accidentally dumped corrosive orange juice over the front of it and we've done the following so far. Let it dry before trying to power it up. I went in there to take a look at the damage. Nothing obvious blown or fried but of course the keyboard was sticky as heck, so I just got a new one and replaced it. Keyboard was mounted in a metal casing and plastic covering so I was hopeful at first that maybe it would only take a good cleaning to get it running again. It was tough to get into with all the little clamps holding it place (like fifty I had to solder out) but no luck with just a cleaning.

He's got schoolwork to do and he says it's slowing him down not to have it but there are plenty of computers on campus so it should be fine for now. He says he can just take it to a repair place but I know he cant really afford it so here we are.

Keyboards been replaced and with the power supply plugged in, it will turn on, but no display. Tried hooking it up to an external device via HDMI but still nothing. Hard reset, nothing either.

Disconnected the battery from the motherboard to see if that was the problem. Battery is for sure dead, as it wont hold a charge but even disconnected there's still no display. Well I'm not sure how to tell which part it is for sure yet. Going to try more troubleshooting after getting the new battery but its slow going. RAM seems OK, but could be the GPU potentially. I dont think it would power on if the motherboard were fried.

Now he's also got two hard drives installed, one HDD and one SSD, so I'm wondering if one is out, whether the other one would go too. I'm pretty sure the operating system would be on the SSD.

Mostly trying to narrow down our options here so we don't have to go piece by piece and ultimately spend weeks replacing each part one by one, ordering one and waiting for another to come in over and over, especially if its a software issue rather than hardware (but odds are hardware since its water damage)

He for Sure cant afford a totally new one and says he needs things still on the hard drives (something about a video project he was working on) so we cant start over either. I could afford to get his hard drives backed up and get him a new one but its a pretty new laptop so I'd rather get it back up and running. Plus I dont want him owing me more than he does already (Im paying part of his tuition) and I know he doesnt want that either (too proud to ask).

TLDR Any technical advice to speed up the project? Do we know what it isn't yet based on these symptoms? Thanks in advance for any help.